Structure and stability of the Si(105) surface

TL;DR

This paper models the Si(105) surface to explain its observed disorder and stability, showing that multiple atomic configurations with similar energies cause surface roughness, which can be stabilized by compressive strain.

Contribution

The study introduces new atomic models for the Si(105) surface based on step-terrace structures and explains surface disorder through energetic degeneracy of these models.

Findings

Multiple structural models have similar energies, causing surface disorder.

Applying compressive strain reduces degeneracy, stabilizing specific structures.

Results align with experimental observations of Ge/Si(105) surfaces.

Abstract

Recent experimental studies have shown that well-annealed, unstrained Si(105) surfaces appear disordered and atomically rough when imaged using scanning tunnelling microscopy (STM). We construct new models for the Si(105) surface that are based on single- and double-height steps separated by Si(001) terraces, and propose that the observed surface disorder of Si(105) originates from the presence of several structural models with different atomic-scale features but similar energies. This degeneracy can be removed by applying compressive strains, a result that is consistent with recent observations of the structure of the Ge/Si(105) surface.